High-strength TC4-BN alloy containing isometric crystal and columnar crystal mixed structure and preparation method of high-strength TC4-BN alloy

Abstract

The invention discloses a high-strength TC4-BN alloy containing an isometric crystal and columnar crystal mixed structure and a preparation method of the high-strength TC4-BN alloy, the addition amount of BN in the TC4-BN alloy is 0.3-0.8 wt%, the microstructure of the alloy is the isometric crystal and columnar crystal mixed structure with the micrometer scale, and the compressive strength of the alloy reaches 1600-2200 MPa. The preparation method comprises the following steps: screening BN powder and TC4 powder, then mixing the BN powder and TC4 powder with stainless steel balls in proportion, and putting the mixture into a ball milling tank; tC4 powder and BN powder are evenly mixed through a planetary ball mill and then stored through vacuum packaging; the mixed powder serves as a raw material, TC4 alloy serves as a substrate, and the TC4-BN alloy is prepared through 3D printing by means of SLM equipment; and the substrate and the 3D printing piece are integrally placed in a vacuum annealing furnace to be subjected to stress relief annealing. According to the preparation method, an isometric crystal and columnar crystal mixed structure is formed in the titanium alloy prepared through SLM by adding the BN, and the alloy strength is remarkably improved through synergistic strengthening of the BN, the TiB, the TiB2 and the TiN; and transformation of a 3D printing titanium alloy microstructure from a columnar crystal orientation isometric crystal and columnar crystal mixed structure is achieved.

Description

technical field [0001] The invention belongs to the technical field of additive manufacturing, and in particular relates to a high-strength TC4-BN alloy containing a mixed structure of equiaxed crystals and columnar crystals and a preparation method thereof. [0002] technical background [0003] The molten pool formed by 3D printing of metal materials has a small size and a large temperature gradient, which makes the layers show the characteristics of epitaxial growth, resulting in the generation of coarse columnar grains along the structural direction, which in turn leads to significant performance anisotropy and reduces mechanical properties. performance and increased hot cracking tendency. In contrast, the fine equiaxed grain structure can improve the performance anisotropy, which is beneficial to reduce thermal stress and reduce the tendency of hot cracking. Therefore, replacing coarse columnar grains with fine equiaxed grains is an important direction for the research ...

AI Technical Summary

Problems solved by technology

Among them, B is a very efficient heterogeneous nucleating agent, which can significantly refine and precipitate β grains in both traditional cast titanium alloys and 3D printed titanium alloys, but its improvement in the strength of titanium alloys is not obvious. Main factors limiting the application of B in titanium alloys, especially 3D printing titanium alloys

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